The present invention relates to a method whereby the manner in which a work is to be machined is determined by the function of preparing numerical control information.
Referring to FIG. 1, a description will be given of a conventional method whereby the manner of machining is determined by the numerical control information preparing function.
In an apparatus to which the conventional method is applied, data denoting the shape of work to be machined and data denoting the shape of a component part into which the work is to be machined are inputted through a keyboard 1 to a work shape storing section 2 and a component part shape storing section 3, respectively. Also, data denoting the shape of various tools which may be used in the machining process such as data denoting the tool angle and the cutting angle, is inputted to a tool shape registering section 6. Similarly, data denoting various machining sequences and data denoting various machining conditions are inputted through the keyboard 1 to a machining sequence registering section 8 and a machining condition registering section 10, respectively.
A machining portion determining section 4 determines the portion of the work which should be machined, by reading the data denoting the work shape and the data denoting the component part shape from the work shape storing section 2 and the component part shape storing section 3, respectively. Data denoting a target configuration WS into which the determined machining portion should be machined is sent to a cutting direction determining section 5 as well as to a machining procedure registering section 12. The cutting direction determining section 5 determines, on the basis of the target configuration WS of the to be machined portion of the work, the direction CD in which cutting should be performed. Data denoting the determined cutting direction CD is sent to a tool determining section 7 and the machining procedure registering section 12. The tool determining section 7 determines, as the tool to be used, a tool that conforms with the cutting direction CD and the work machining portion target configuration WS that has been read from the machining procedure registering section 12, by selecting a tool shape, from among various tool shapes registered in the section 6. Data denoting the determined tool DT to be used is sent to the machining procedure registering section 12. When the tool to be used has been thus selected and determined by the tool determining section 7, if the selected tool shape is such that any part of the work portion that should be machined will remain uncut, this possibility is posted to a remaining uncut part determining section 14.
In this case, the remaining uncut part determining section 14 reads, from the machining procedure registering section 12, the work machining portion target configuration of part of the to be machined portion of the work which will remain uncut after machining, and changes the work machining portion target configuration into a configuration in which the work machining portion can be machined without any uncut portion remaining after machining. The section 14 sends data on the corrected target configuration of the work machining portion to the machining procedure registering section 12. The section 14 also operates to determine the target configuration into which the part remaining uncut after the first machining process should be further machined, and then sends data denoting the determined target configuration to the machining procedure registering section 12 as well as to the cutting direction determining section 5. With respect to the part remaining uncut after the first machining process, the cutting direction determining section 5 and the tool determining section 7 perform operations similar to those described above, that is, they respectively determine the cutting direction and the tool to be used to machine the remaining uncut portion.
A machining sequence determining section 9 reads, from the machining procedure registering section 12, the data denoting the target configuration WS of the machining portion, the cutting direction CD, and the tool DT to be used, these data being already registered. On the basis of the read data, the section 9 determines the sequence WR to be followed during machining, in accordance with data registered in the machining sequence registering section 8. The determined machining sequence WR is sent to a cutting condition determining section 11 and the machining procedure registering section 12. The cutting condition determining section 11 determines the cutting conditions to be adopted during machining in accordance with data registered in the cutting condition registering section 10, and on the basis of the data denoting the target configuration WS of the machining portion, the cutting direction CD, the tool DT to be used, and the machining sequence WR read from the machining procedure registering section 12 in which such data is already registered. The determined cutting conditions are sent to the machining procedure registering section 12 and are then registered therein. Finally, a numerical control information preparing section 13 prepares numerical control information NCF in accordance with the above-described data registered in the machining procedure registering section 12.
As an example, a case will be described in which the apparatus shown in FIG. 1 is used to obtain a component part having the shape indicated by the solid line shown in FIG. 2 from a workpiece having the shape indicated by the broken line shown in FIG. 2. A determination is made by the machining portion determining section 4 as to the target configuration into which the outer diameter of a portion of the work should be machined, specifically, the configuration defined by the lines or configuration constituents l.sub.1, l.sub.2, l.sub.3, l.sub.4, l.sub.5, l.sub.6, l.sub.7, l.sub.8 and l.sub.9 shown in FIG. 2. The cutting direction is determined, by the cutting direction determining section 5, to be the forward direction, as indicated by the arrow shown in FIG. 3 (the hatching indicates the part to be machined in the forward cutting direction). Further, the tool to be used is determined by the tool determining section 7. Thereafter, the machining sequence and the cutting conditions are determined, thereby allowing the preparation of numerical control information NCF.
Another case will be described, in which a component part having the shape indicated by the solid line shown in FIG. 4 is to be obtained from a workpiece having the configuration indicated by the broken line shown in FIG. 4. A determination is made by the machining portion determining section 4 as to the target configuration that should be achieved in a portion of the work by subjecting the work to outer diameter machining, specifically, the configuration defined by the lines l.sub.1, l.sub.2, l.sub.3, l.sub.4, l.sub.5, l.sub.6, l.sub.7, l.sub.8 and l.sub.9 shown in FIG. 4. The cutting direction is determined, by the cutting direction determining section 5, to be the forward direction, as indicated by the arrow shown in FIG. 5 (the hatched lines declining to the left indicating the part to be machined in the forward cutting direction). Further, the tool to be used is determined by the tool determining section 7. In this case, however, a part of the machining portion will remain uncut after the forward cutting machining, such as that indicated by the hatched lines declining to the right in FIG. 5. Therefore, a correction is performed by the remaining uncut part determining section 14 such that the target configuration that should be first achieved by the portion to be subjected to the outer diameter machining is determined to be the configuration defined by the lines l.sub.1, l.sub.2, l.sub.3, l.sub.4, l.sub.5, l.sub.7 '", l.sub.7 ", l.sub.8 and l.sub.9, while the target configuration that should be achieved by the part remaining uncut after the first forward direction machining process is determined to be the configuration defined by the lines l.sub.7 ' and l.sub.6. Furthermore, the cutting direction and the tool that are to be used in the machining of the remaining uncut part are determined by the sections 5 and 7, respectively.
With this method, however, the following problem arises. The constituent l.sub.7 among the constituents defining the target configuration of the outer diameter machining portion is divided, at a point P, into the two subconstituents, i.e., l.sub.7 " which is to be achieved by forward cutting, and l.sub.7 ' which is to be achieved by backward cutting. As a result, a mark will be formed at the dividing point P, and such a mark will remain after the completion of the machining.
In order to avoid this problem, when numerical control information NCF is to be prepared by normal manual mode, the conventional practice that has been generally adopted is to divide the entire outer diameter machining portion into sub-portions at a point P.sub.0, as shown in FIG. 6. This allows the configuration constituents l.sub.1, l.sub.2, l.sub.3, l.sub.4 and l.sub.5 to be achieved by machining in the forward direction, whereas the configuration constituents l.sub.9, l.sub.8, l.sub.7 and l.sub.6 to be achieved by machining in the backward direction. However, this conventional practice also necessitates one constituent of the configuration to be divided in the middle, thereby resulting in the preparation of numerical control information that can adversely affect the machined surface.
As described above, the conventional method has been such that a portion of work which is to be subjected to outer diameter machining as well as a portion of the work which is to be subjected to inner diameter machining are determined on the basis of the inputted data denoting the shape of the workpiece and denoting the shape of the component part to be obtained, the cutting direction to be used in the machining process is always determined to be the forward direction relative to each of the machining portions, and the tool to be used is determined on the basis of the target configuration of each machining portion and on the basis of the cutting direction. Then, a check is made, on the basis of the target configuration of each machining portion, the cutting direction, and the shape of the tool to be used, whether cutting is possible without involving any interference of the tool with the configuration of each machining portion, a new route is created if such interference is possible, and, finally, a part remaining uncut after the completion of the machining performed in the above-described manner is removed by performing machining in the backward direction. However, the conventional method always necessitated one constituent of the target configuration corresponding to the component part shape to be divided, in the middle thereof, into a sub-portion to be subjected to forward cutting and a sub-portion to be subjected to backward cutting. This has lead to adverse influences on the machined surface.